## Search found 20 matches

Sat Mar 12, 2016 6:58 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Determining whether the change in entropy is + or -
Replies: 1
Views: 278

### Re: Determining whether the change in entropy is + or -

In this example, you are going from 3 moles of gas to 2 moles of gas. There is less disorder and hence, entropy decreases in this case.
Tue Mar 08, 2016 1:57 am
Forum: *Alkenes
Topic: Sum of numbers
Replies: 1
Views: 354

### Re: Sum of numbers

You actually never use the sum of numbers. Although it may seem to hold true sometimes, it is not actually a IUPAC rule.
Mon Feb 29, 2016 3:02 pm
Forum: *Alkanes
Topic: Quiz #3 Prep #5 priority on alkanes??
Replies: 1
Views: 298

### Re: Quiz #3 Prep #5 priority on alkanes??

You order the substituents alphabetically! In this case, bromo comes before iodo which is why it is 3-bromo-1-iodohexane.
Tue Feb 23, 2016 1:21 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Structure for the activated complex (HW 15.85)
Replies: 3
Views: 624

### Re: Structure for the activated complex (HW 15.85)

In the course reader (pg. 71), it indicates that molecularity is the number of species in an elementary step. In this case, there are two iodine and one argon as reactants. In its generic form, this would be A + A + B ---> P which is termolecular.
Fri Feb 19, 2016 1:52 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Sig figs
Replies: 2
Views: 436

### Re: Sig figs

You would add a zero so that there are two sig figs.

Also, Im unsure about your second question but if 1 hr was a conversion factor, then you would disregard it.
Tue Feb 09, 2016 12:29 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: q=mCs delta T and q=nC delta T
Replies: 1
Views: 5656

### Re: q=mCs delta T and q=nC delta T

For q = mCs delta T, m is for the mass (in grams) whereas in q= nC delta T, n is for the number of moles you have. You use either equation depending on what is given.
Fri Feb 05, 2016 12:40 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Relationship between internal energy and temperature
Replies: 4
Views: 3228

### Re: Relationship between internal energy and temperature

Internal energy is directly proportional to temperature. So if there is an increase in temperature, there is also an increase in internal energy.
Fri Jan 29, 2016 3:04 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Question 12 Quiz Preparation winter 2014
Replies: 2
Views: 324

### Re: Question 12 Quiz Preparation winter 2014

^ It is like what Pranay said above. This is because when delta G is negative, then the reaction is spontaneous. If delta G is positive, the reaction is non-spontaneous. Hence by setting delta G equal to zero, you are finding in a sense the threshold temperature for the reaction to be spontaneous.
Tue Jan 19, 2016 3:01 pm
Forum: Calculating Work of Expansion
Topic: Irreversible vs reversible expansion
Replies: 3
Views: 633

### Re: Irreversible vs reversible expansion

For a reversible expansion, there is an equal pressure between the external environment and the system itself. Hence, an integral must be used to calculuate the continuity of the change in work. However, in an irreversible expansion, the external pressure is constant and the work can be calculated u...
Mon Jan 11, 2016 10:19 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.73
Replies: 2
Views: 379

### Re: 8.73

Continuing from what is said above, using either values of bond enthalpies or those of standard enthalpies of formations, you will arrive at the same delta H value.
Sun Nov 29, 2015 11:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Video: Quiz 3, Question 7
Replies: 1
Views: 301

### Re: Video: Quiz 3, Question 7

Sun Nov 29, 2015 10:44 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Video: Quiz 3, Question 7
Replies: 1
Views: 301

### Video: Quiz 3, Question 7

There is a slight error in the Gly-Ala equilibrium concentration in the video. 3.21 x 10^4 M is indeed the final answer but when subtracting x from 0.01 M, the answer should be 0.000320707 instead of 0.0032707, which was written in the video.
Thu Nov 26, 2015 3:24 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Trend to Remembering Strong Acids
Replies: 2
Views: 551

### Trend to Remembering Strong Acids

Is there an easy way or general trend to remember which acids are strong acids?
Thu Nov 12, 2015 11:54 am
Forum: Equilibrium Constants & Calculating Concentrations
Replies: 2
Views: 765

In lecture, I believe Dr. Lavelle mentioned that there will only be one answer that works. If you get two positive answers, plug each answer into the original equation to double check that it works. Or sometimes, one value is greater than the initial concentration which is not plausible. However, I ...
Fri Nov 06, 2015 12:12 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Drawing MO Energy Diagrams
Replies: 3
Views: 483

### Re: Drawing MO Energy Diagrams

When drawing the molecular orbital diagrams, the more electronegative element is "pushed down" because it has a lower energy level. This is because the lone pairs of the atom are more stable and thus lower in energy.
Wed Oct 28, 2015 2:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Resonance vs Double bonds
Replies: 1
Views: 305

### Re: Resonance vs Double bonds

For NO2-, the Lewis Structure isn't drawn as O = N = O because when you do this, there are only 16 electrons being represented where as NO2- has 18 electrons. For SO2, I believe it is the same reasoning, too.
Thu Oct 22, 2015 8:53 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Nitrogen and Oxygen Bonding
Replies: 2
Views: 338

### Re: Nitrogen and Oxygen Bonding

In this case, NO (nitric oxide) is a free radical due to the unpaired electron on N. However, I believe it is still in a linear shape.
Sun Oct 18, 2015 1:00 pm
Forum: Electronegativity
Topic: Calculating Electronegativity
Replies: 2
Views: 452

### Re: Calculating Electronegativity

Electronegativity decreases down a periodic group, because as the atomic radii increases, the electrons move farther away from the nucleus and are thus easier to remove. Likewise, electronegativity increases across a row because with more protons, there is a greater pull on the remaining electrons. ...
Fri Oct 09, 2015 7:24 pm
Forum: Trends in The Periodic Table
Topic: Isoelectronic
Replies: 2
Views: 383

### Re: Isoelectronic

Like what was said above, when there is an increase in protons, the ionic radius decreases. This is because the more protons there are, the greater the nuclear charge - meaning that the electrons are pulled closer towards the nucleus. In this specific problem, Mg2+ would have the smallest atomic rad...
Fri Oct 02, 2015 11:02 am
Forum: Properties of Light
Topic: 1.3 manipulating light equations
Replies: 3
Views: 615

### Re: 1.3 manipulating light equations

Similar to what was said above, if you look at the equation c = λv (v as in frequency), then when frequency is decreasing, the wavelength must be increasing in order for c to be a constant. Since the wavelength is increased/elongated, it has a smaller slope and therefore a decrease in the extent of ...